Method and apparatus for sterilizing sterilization filter unit

ABSTRACT

To sterilize a sterilization filter unit with heated steam, minimize the heat load on the sterilization filter unit and extend the service life of the sterilization filter unit.Heated steam is supplied to a sterilization filter unit that sterilizes supplied air, the temperature of the heated steam discharged from the sterilization filter unit is measured at predetermined time intervals, the F value is calculated from the measured temperature, and sterilization of the sterilization filter unit is ended when the F value reaches a target value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.16/762,990, filed May 11, 2020, which in turn is the National Stageentry of International Application No. PCT/JP2018/044878 filed Dec. 6,2018, which designated the United States, the entireties of which areincorporated herein by reference, and claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2017-236009 filed on Dec. 8,2017.

FIELD OF THE INVENTION

The present invention relates to a method and an apparatus forsterilizing a sterilization filter unit that removes bacteria or thelike in air used in an aseptic filling machine.

BACKGROUND OF THE INVENTION

An aseptic filling machine that aseptically fills a bottle with a drinkor the like uses compressed aseptic air for various purposes, such asremoval of foreign matters from a preform fed, spraying of a sterilizerused for sterilizing the preform, removal of the sterilizer, blowmolding of the preform into a bottle, blasting of aseptic air to thesterilized preform to keep the preform aseptic while the preform isbeing conveyed, spraying of a sterilizer used for sterilizing thebottle, removal of the sterilizer and shooting of a cap when feeding thecap. Air piping through which the compressed aseptic air is supplied anda sterilization filter unit that removes bacteria or the like have to besterilized before operation of the aseptic filling machine.

The piping for the compressed aseptic air and the sterilization filterunit are typically sterilized by heated steam. However, the steamsterilization has a problem that the service life of the sterilizationfilter unit decreases, and a method of sterilizing the sterilizationfilter unit with hydrogen peroxide has been proposed (Patent Literatures1 and 2). Patent Literature 1 discloses that a hydrogen peroxidesolution is sprayed and then heated for gasification, and the resultinghydrogen peroxide gas is fed to a sterilization filter unit. PatentLiterature 2 discloses that hydrogen peroxide is supplied into airpiping, and the hydrogen peroxide deposited in the piping is evaporatedand fed to a filter by heated air. In both the methods, thesterilization filter unit is sterilized by gasified hydrogen peroxide.In short, for sterilizing the sterilization filter unit, there aremethods of using heated steam and methods of using gasified hydrogenperoxide.

Drink supply piping of an aseptic filling machine is typicallysterilized by hot water or steam. To prevent excessive sterilization,introducing F value management has been proposed. For example, it hasbeen proposed that, when sterilizing by heating with hot water or steamthe drink supply piping for feeding a drink from a drink heating andsterilization portion into the filling machine, the temperature of thedrink supply piping is measured at a plurality of locations atpredetermined time intervals to calculate the F value at the locations,and the sterilization process is ended when the minimum of the F valuesreaches a target value (Patent Literature 3).

It has also been proposed that, when feeding hot water or steam into thedrink supply piping that feeds a drink to filling nozzles to sterilizethe inside of the filling nozzles with the hot water or steam ejectedfrom the filling nozzles, the temperature of the inside of all thefilling nozzles is detected at predetermined time intervals to calculatethe F value for the filling nozzles, and the sterilization process isended when the minimum of the F values reaches a target value (PatentLiterature 4).

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Patent Laid-Open No. 10-16925-   Patent Literature 2: Japanese Patent Laid-Open No. 2017-42309-   Patent Literature 3: International Publication No. W02014-103787-   Patent Literature 4: Japanese Patent Laid-Open No. 2015-6920

SUMMARY OF THE INVENTION Technical Problem

A sterilization filter unit that sterilize compresses air is sterilizedwith heated steam or gasified hydrogen peroxide. However, there is aproblem that the sterilization filter unit has various parts made ofresin, such as a support for a filter material, the filter material, anO-ring, and an end cap, and the resin deteriorates because of the heatof the heated steam and the gasified hydrogen peroxide, so that theservice life of the sterilization filter unit is shortened.

Hydrogen peroxide has a problem that hydrogen peroxide is adsorbed bythe resin forming the sterilization filter unit and remains therein, sothat heated steam is preferably used for sterilization. However, whenthe heated steam is used for sterilization of the sterilization filterunit, the heat load on the resin forming the sterilization filter unitis high, and the resin can deteriorate. To avoid this, there is a demandfor a method and an apparatus for sterilizing a sterilization filterunit that minimize the heat load on the sterilization filter unit andextend the service life of the sterilization filter unit.

An object of the present invention is to provide a method and anapparatus for sterilizing a sterilization filter unit that can solve theproblems described above.

Solution to Problem

In a method for sterilizing a sterilization filter unit according to thepresent invention, heated steam is supplied to the sterilization filterunit, which sterilizes supplied air, a temperature of the heated steamdischarged from the sterilization filter unit is measured atpredetermined time intervals, an F value is calculated from the measuredtemperature, and sterilization of the sterilization filter unit is endedwhen the F value reaches a target value.

In the method for sterilizing a sterilization filter unit according tothe present invention, the F value is preferably calculated according tothe following formula:

F = ∫_(t₀)^(t₁)10^((T − Tr)/Z)dt

wherein T is an optional sterilizing temperature (° C.), 10^((T-Tr )/Z)is a fatality rate at the optional temperature T, Tr is a referencetemperature (° C.), and Z is a Z value (° C.).

In the method for sterilizing a sterilization filter unit according tothe present invention, the supplied air is preferably air having apressure equal to or higher than 0.01 MPa.

In the method for sterilizing a sterilization filter unit according tothe present invention, the air is preferably supplied to thesterilization filter unit after dust, oil or moisture is removed fromthe air.

In an apparatus for sterilizing a sterilization filter unit according tothe present invention, a heated steam supply device is provided betweenan air supply apparatus and the sterilization filter unit, whichsterilizes air supplied from the air supply apparatus, heated steam issupplied to the sterilization filter unit from the heated steam supplydevice, a temperature sensor is provided which measures a temperature ofthe heated steam discharged from the sterilization filter unit, thetemperature of the discharged heated steam is measured at predeterminedtime intervals, a calculation apparatus is provided which calculates anF value from the measured temperature, and sterilization of thesterilization filter unit is ended when the F value reaches a targetvalue.

Advantageous Effects of Invention

According to the present invention, in an aseptic filling machine, whensterilizing a sterilization filter unit that sterilizes compressed airused for removal of foreign matters from a preform fed, spraying of asterilizer for sterilizing the preform, removal of the sterilizer, blowmolding of the preform into a bottle, blasting of aseptic air to thesterilized preform to maintain the aseptic condition of the preformduring conveyance thereof, spraying of a sterilizer for sterilizing thebottle, removal of the sterilizer, and shooting of a cap when feedingthe cap, for example, heated steam used for the sterilization is managedthrough F-value control. Therefore, it is no longer required tounnecessarily raise the temperature of the heated steam or tounnecessarily extend the time for which the heated steam is supplied tothe sterilization filter unit, so that the sterilization time can bereduced, the heat load on the sterilization filter unit can be reduced,and the service life of the sterilization filter unit can be extended.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a circuit diagram showing a configuration for sterilizing asterilization filter unit according to an embodiment of the presentinvention.

FIG. 2 is a circuit diagram showing a configuration for sterilizing airsupply piping for supplying air to an aseptic filling machine accordingto the embodiment of the present invention.

FIG. 3 is a circuit diagram showing a configuration during operation ofthe aseptic filling machine according to the embodiment of the presentinvention.

FIG. 4 is a graph showing a relationship between the temperature ofheated steam and the sterilization time in sterilization of thesterilization filter unit according to the embodiment of the presentinvention.

FIG. 5 is a graph showing a relationship between the temperature ofheated steam and the sterilization time in conventional sterilization ofthe sterilization filter.

FIG. 6 shows a cross section of an apparatus that supplies hydrogenperoxide when sterilizing piping for compressed air according to theembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following, an embodiment of the present invention will bedescribed with reference to the drawings.

In an aseptic filling machine, an aseptic chamber 1 houses a sterilizingmachine that sterilizes a container to be sterilized, such as a bottle,a washing apparatus that washes the sterilized container, a fillingapparatus that fills the washed container with a sterilized content, asterilizing apparatus for a lid member that seals the container filledwith the content, a sealing apparatus that seals the container with thesterilized lid member and a discharge apparatus that discharges thesealed container to the outside of the aseptic filling machine, forexample, and air is supplied into the aseptic chamber 1 from an airsupply apparatus 2 through air supply piping, as shown in FIG. 1 .

The air supplied from the air supply apparatus 2 to the aseptic chamber1 is sterilized by a sterilization filter unit 4 removing bacteria orthe like from the air. When the aseptic filling machine is out ofservice, the aseptic chamber 1 is opened and therefore contaminated withbacteria or the like. The air in the aseptic chamber 1 thus contaminatedcan flow back through the air supply piping and contaminate thecomponents downstream of the sterilization filter unit 4. Besides, thesterilization filter unit 4 is replaced after being used for apredetermined length of time, and the surface of a new replacementsterilization filter unit 4 is contaminated with bacteria or the like.

Therefore, when the aseptic filling machine is restarted after beingstopped or after replacement of the sterilization filter unit 4, thesterilization filter unit 4 has to be sterilized. In addition, the partof the inside of the air supply piping from the sterilization filterunit 4 to the aseptic chamber 1 has to also be sterilized.

FIG. 1 is a circuit diagram showing a configuration for sterilizing thesterilization filter unit 4. An on-off valve 6 connected to the airsupply apparatus 2 is closed, and heated steam is supplied to thesterilization filter unit 4 from a heated steam supply device 3, whichis provided between the air supply apparatus 2 and the sterilizationfilter unit 4 that sterilizes the air supplied from the air supplyapparatus 2. In this step, on-off valves 7, 8 and 11 are open. Theheated steam supplied from the heated steam supply device 3 is suppliedto the sterilization filter unit 4 and discharged through the on-offvalve 11. In FIGS. 1, 2 and 3 , the on-off valves colored black areclosed, and the on-off valves colored white are open.

A temperature sensor S is provided at a location downstream of thesterilization filter unit 4 and downstream of the on-off valve 11. Whenthe heated steam is supplied to the sterilization filter unit 4, thetemperature of the discharged heated steam is measured by thetemperature sensor S at predetermined time intervals, the resultingtemperature measurement information is transmitted to a controller 15,and the controller 15, which includes a calculation apparatus thatcalculates the F value, calculates the F value. When the F value reachesa target value, the supply of the heated steam from the heated steamsupply device 3 is stopped in response to a signal from the controller15, and the sterilization of the sterilization filter unit 4 is ended.

The F value is determined from the temperature measured by thetemperature sensor S and transmitted to the controller 15 according tothe following formula.

F = ∫_(t₀)^(t₁)10^((T − Tr)/Z)dt

wherein T is an optional sterilizing temperature (° C.), 10^((T-Tr)/Z)is a fatality rate at the optional temperature T, Tr is a referencetemperature (° C.), and Z is a Z value (° C.).

Provided that Tr in the formula is 121.1° C., when the temperaturemeasured by the temperature sensor S reaches 121.1° C., the calculationapparatus in the controller 15 starts calculating the F value. The Zvalue for spore fungus to be killed is 7° C. to 11° C. For example, thecalculation can be performed on the assumption that the Z value is 10°C. The Z value and the target F value can be arbitrarily set to thelevel of sterilization required for the content to be charged by theaseptic filling machine.

When the pH of the content is equal to or more than 4 and less than 4.6,the reference temperature Tr can be set at 85° C., and the Z value canbe set at 7.8° C. When the pH of the content is less than 4, thereference temperature Tr can be set at 65° C., and the Z value can beset at 5° C., although the values can be changed as required. When thepH is equal to or more than 4.6, the calculation can be performed on theassumption that the reference temperature Tr is 121.1° C. and the Zvalue is 10° C.

As shown in FIG. 4 , the calculation of the F value starts when thetemperature measured by the temperature sensor S reaches 121.1° C., andthe sterilization ends when the F value, which is calculated from thetemperature measured by the temperature sensor S and is represented bythe area of the hatched part, reaches a target value. FIG. 5 shows anexample of conventional art, in which a timer starts 10 minutes afterthe start of supply of the heated steam when the temperature measured bythe temperature sensor S provided on the heated steam discharge pipereaches 130° C., the sterilization ends 30 minutes after the start ofthe timer, and then the sterilization filter unit 4 is cooled over 5minutes. That is, it takes approximately 45 minutes to sterilize thesterilization filter unit 4 from the start of the sterilization to theend of the cooling. In FIG. 4 , since the sterilization time is managedbased on the F value, it takes 5 minutes for the temperature to rise to121.1° C., it takes 8 minutes for the F value to reach an F₀=233 (whichis equivalent to the effect of the sterilization performed at 130° C.for 30 minutes), and it takes about 5 minutes to cool the sterilizationfilter unit 4. That is, the total time until the end of the cooling is18 minutes, which is about 60% shorter, in terms of the time requiredfor sterilizing the sterilization filter unit 4, than 45 minutes, whichis the total time in the case of conventional art.

In addition to the time required to sterilize the sterilization filterunit 4, the time for which the sterilization filter unit 4 is exposed tothe heated steam can also be reduced, and the temperature of the heatedsteam to which the sterilization filter unit 4 is exposed can also bereduced. As a result, the deterioration of the support member for thefilter material, the filter material, the O-ring, the end cap and thelike of the sterilization filter unit 4 can be reduced, and the servicelife of the sterilization filter unit 4 can be extended.

The heated steam supply device 3 heats water into steam by the heat fromelectricity or fuel, and the water used may be purified through areverse osmosis membrane. A storage water heater body for changing waterinto steam is exposed to a boiler compound, a condensate treatment agentor the like, and the food additive grade is used for these agents. Thestorage water heater body and conveyance piping are preferably made ofstainless steel. The heated steam may be passed through a filter,activated carbon, or an ultrafilter to remove foreign matters, ions,chemicals or the like from the heated steam. Furthermore, the heatedsteam supply device 3 is preferably a reboiler that produces heatedsteam through heat exchange between water passed through a reverseosmosis membrane and heated steam as a heat source.

The temperature of the heated steam supplied to the sterilization filterunit 4 is 121.1° C. to 150° C. A temperature lower than 121.1° C. is toolow for sterilizing, and a temperature higher than 150° C. can causedeterioration of the members of the sterilization filter unit 4.

The sterilization filter unit 4 has a hollow cylindrical shape. A hollowcylindrical filter is housed in a removable housing and attached to thehousing in such a manner that the filter can be inserted into thehousing. The housing has an air inlet port through which air can besupplied into the hollow cylindrical filter unit from outside and adischarge port through which air having passed through a hollow portionof the hollow cylindrical filter unit is discharged. The housing has adrain reservoir at a lower part thereof, and an automatic drain trapthat is in communication with the drain reservoir is attached to thehousing.

The filter of the sterilization filter unit 4 can remove bacteria, mold,spore or the like. The filter has pores having a diameter ofapproximately 0.1 μm to 0.5 μm and is made of regenerated cellulose,nitrocellulose, or polytetrafluoroethylene, for example. Thesterilization filter unit 4 is formed by placing such a filter havingpores between support members that are non-woven fabric of polypropyleneor cellulose, folding the resulting stack into a hollow shape,reinforcing the inside and outside of the resulting hollow body withmesh-like support cores made of stainless steel, and closing the top andbottom ends of the hollow body with end caps made of a heat resistantplastic material, such as polyphenylsulfone. The discharge port fordischarging air from the hollow portion is formed in one of the endcaps, and the discharge port of the housing is fixed to the piping viaan O-ring made of silicon rubber or the like.

After the heated steam starts being supplied to the sterilization filterunit 4, when the F value calculated from the temperature measured by thetemperature sensor S reaches a target value, the sterilization of thesterilization filter unit 4 is ended, and as shown in FIG. 2 , theon-off valves 7, 8 and 11 are closed, the on-off valves 9 and 10 areopened to sterilize the part of the inside of the air supply piping fromthe on-off valve 8 located downstream from the sterilization filter unit4 to the aseptic chamber 1. If this part is also sterilized with theheated steam, the time for which the sterilization filter unit 4 isexposed to the heated steam is extended to cause deterioration of themembers of the sterilization filter unit 4. For this reason, thesterilization with the heated steam is used only for limited parts ofthe apparatus for sterilizing the sterilization filter unit 4. The partof the inside of the air supply piping from the on-off valve 8 to theaseptic chamber 1 is sterilized with a sterilizer, such as hydrogenperoxide or peracetic acid.

FIG. 2 shows a circuit diagram showing a configuration for sterilizingthe part of the inside of the air supply piping from the on-off valve 8to the aseptic chamber 1. First, a sterilizer supply apparatus 5supplies a sterilizer into the part of the inside of the air supplypiping from the on-off valve 9 to the aseptic chamber 1. As shown inFIG. 6 , the sterilizer supply apparatus 5 includes a sterilizersupplying portion 12 that is a twin-fluid spray nozzle for supplying thesterilizer in the form of liquid drops and an evaporating portion 13 forevaporating the sterilizer supplied from the sterilizer supplyingportion 12 by heating the sterilizer to a temperature equal to or lowerthan the decomposition temperature thereof. The sterilizer supplyingportion 12 is configured to take in the sterilizer from a sterilizersupply path 12 a and compressed air from a compressed air supply path 12b and then sprays the sterilizer into the evaporating portion 13. Theevaporating portion 13 is a pipe with a heater 13 a interposed betweeninner and outer walls thereof, and the sterilizer blasted into the pipeis heated and evaporated. The evaporated sterilizer gas is jetted out ofthe evaporating portion 13 at a lower end of the evaporating portion 13.Instead of using the heater 13 a, the evaporating portion 13 may beheated by dielectric heating.

A sterilizer blasting nozzle 14 is coupled to the lower end of theevaporating portion 13, and gas or mist of the sterilizer or a mixturethereof is blasted from the sterilizer blasting nozzle 14 into the partof the air supply piping to the aseptic chamber 1. The sterilizerblasted into the part of the air supply piping to the aseptic chamber 1is in the form of gas or mist or a mixture thereof, because thesterilizer gasified in the evaporating portion 13 can be condensed intomist before the sterilizer is blasted from the sterilizer blastingnozzle 14.

Heated aseptic air may be supplied at a location between the lower endof the evaporating portion 13 and the sterilizer blasting nozzle 14,thereby mixing the heated aseptic air with the gas or mist of thesterilizer or a mixture thereof generated by the sterilizer supplyapparatus 5.

With regard to operational conditions of the sterilizer supplyingportion 12 of the sterilizer supply apparatus 5, the pressure of thecompressed air is adjusted to fall within a range from 0.05 MPa to 0.6MPa, for example. The sterilizer may be supplied by gravity or underpressure. The amount of the supplied sterilizer can be arbitrarily set.For example, the amount of the supplied sterilizer falls within a rangefrom 1 g/min. to 100 g/min. The inner surface of the evaporating portion13 is heated to 140° C. to 450° C. to evaporate the sprayed sterilizer.

The sterilizer preferably contains at least hydrogen peroxide. Anappropriate content of hydrogen peroxide falls within a range from 0.5%by mass to 65% by mass. If the content is less than 0.5% by mass, thesterilizing power may be insufficient. If the content is more than 65%by mass, it is difficult to safely handle the sterilizer. Furthermore, amore preferable content is 0.5% by mass to 40% by mass. If the contentis equal to or less than 40% by mass, the sterilizer can be more easilyhandled.

Although the sterilizer contains water, the sterilizer may contain oneor more of alcohols such as methyl alcohol, ethyl alcohol, isopropylalcohol, n-propyl alcohol and butyl alcohol, ketones such as acetone,methyl ethyl ketone and acetyl acetone, and glycol ethers, for example.

The sterilizer may further contain, as an additive agent, a compoundhaving a sterilizing effect such as peracetic acid, acetic acid, achlorine compound, sodium hydroxide, an alkaline compound such aspotassium hydroxide, nitrous acid, ozone, or acid water, a cationicsurface active agent, a non-ionic surface active agent, a phosphatecompound, or the like.

After the sterilizer is supplied into the part of the air supply pipingfrom the on-off valve 8 to the aseptic chamber 1, heated aseptic air orroom-temperature aseptic air may be supplied into the air supply pipingin order to remove the sterilizer remaining in the air supply piping andto increase the sterilization effect by heating the remainingsterilizer. The aseptic air may be supplied into the air supply pipingfrom the air supply apparatus 2 through the sterilization filter unit 4with the on-off valves 6, 8 and 10 open and the on-off valves 7, 9 and11 closed.

After the sterilizer remaining in the part of the air supply piping fromthe on-off valve 8 to the aseptic chamber 1 is removed, aseptic air maybe supplied into the air supply piping from the air supply apparatus 2with the on-off valves 6 and 8 open and the on-off valves 7, 9, 10 and11 closed as shown in FIG. 3 , until operation of the aseptic fillingmachine is started. This is intended to maintain the aseptic conditionof keep the interior of the air supply piping.

The air supply apparatus 2 is an air compressor, for example, and isdriven by continuous or intermittent operation of a motor to supply air.The motor rotates to feed atmosphere into a tank of the air compressor,and the pressure in the tank increases. A pressure detection sensor isprovided in the tank, and the motor stop rotating when the pressure inthe tank reaches a preset upper limit value. The pressure in the tankdecreases as the air is used, and when the pressure sensor detects apressure equal to or lower than a preset lower limit value, the motorrestarts, and the pressure in the tank increases. The pressure of thesupplied air in this embodiment falls within a range from 0.01 MPa to4.9 MPa. Low-pressure air is used for conveyance of caps or by an airblow gun used in the aseptic chamber of the aseptic filling machine, forexample. High-pressure air is used as blow air for molding preforms intobottles in the aseptic filling machine. The air may be supplied with ablower, instead of the air compressor.

The air supplied by the air compressor contains dust, moisture, oil,organic chemical compounds or the like. A filter for removing thesesubstances is preferably provided between the air supply apparatus 2 andthe on-off valve 6. An air dryer for cooling the air supplied from theair supply apparatus 2 to condense moisture in the air is provided. Thecondensate is discharged through an automatic drain discharge valveprovided in a lower part of the air dryer. Furthermore, a filter havingpores having a diameter greater than 0.5 μm can be provided to removedust and oil. Furthermore, a filter formed by fibers or grains ofactivated carbon may be provided to adsorb and remove organic chemicalcompounds into the activated carbon. Any impurities such as dust,moisture, oil or organic chemical compounds are preferably removed fromthe air before the air is supplied to the sterilization filter unit 4.If such impurities are removed by the sterilization filter unit 4, theservice life of the sterilization filter unit 4 may be shortened.

Although the present invention is configured as described above, thepresent invention is not limited to the embodiment described above, andvarious modifications can be made without departing from the spirit andscope of the present invention.

REFERENCE SIGNS LIST

-   1 aseptic chamber-   2 air supply apparatus-   3 heated steam supply device-   4 sterilization filter unit-   5 sterilizer supply apparatus-   S temperature sensor

1. An apparatus for sterilizing a sterilization filter unit, wherein aheated steam supply device is provided between an air supply apparatusand the sterilization filter unit, which sterilizes air supplied fromthe air supply apparatus, heated steam is supplied to the sterilizationfilter unit from the heated steam supply device, a temperature sensor isprovided which measures a temperature of the heated steam dischargedfrom the sterilization filter unit, the temperature of the dischargedheated steam is measured at predetermined time intervals, a calculationapparatus is provided which calculates an F value from the measuredtemperature, and sterilization of the sterilization filter unit is endedwhen the F value reaches a target value, and a sterilizer supplyapparatus is provided to supply a sterilizer into a part of the insideof an air supply piping for sterilizing from an on-off valve locateddownstream the sterilization filter unit to an aseptic chamber with anon-off valve to supply the heated steam, the on-off valve locateddownstream the sterilization filter unit and the on-off valve todischarge the heated steam closed, and an on-off valve located upstreamthe chamber opened after sterilizing the sterilization filter unit,wherein the apparatus for sterilizing a sterilization filter unit isconfigured to supply an aseptic air through the sterilization filterunit into the air supply piping in order to remove the sterilizerremaining in the air supply piping with an on-off valve to supply air tothe sterilization filter unit and the on-off valve located downstreamthe sterilization filter unit opened, and an on-off valve to supply thesterilizer closed after supplying the sterilizer, and the apparatus forsterilizing a sterilization filter unit is configured to supply theaseptic air into the air supply piping to maintain the aseptic conditionof the interior of the air supply piping with the on-off valve locatedupstream the chamber closed after removing the sterilizer remaining. 2.The apparatus for sterilizing a sterilization filter unit according toclaim 2, wherein the F value is calculated according to the followingformula: $\begin{matrix}{F = {\int_{t_{0}}^{t_{1}}{10^{{({T - {Tr}})}/Z}{dt}}}} & \left\lbrack {{Math}.1} \right\rbrack\end{matrix}$ (wherein T is an optional sterilizing temperature (°C),10^((T-Tr)/Z) is a fatality rate at the optional temperature T, Tr is areference temperature (°C), and Z is a Z value (°C).)